DESCRIPTION (Applicant's Abstract): The central hypothesis of this proposal is that site and sequence specific insertion of genes into eukaryotic chromosomes can be carried out with Tn7 transpositional proteins. The overall objective is to establish a biological basis for gene therapy based on the use of transposon Tn7 proteins. Tn7 was selected for its ability to integrate into a DNA sequence with specificity and efficiency. Preliminary data support a hypothesis that Tn7 based insertion could provide a safe and efficient method to incorporate therapeutic genes into chromosomes. The central hypothesis will be tested in three Specific Aims: 1.Will Tn7 proteins transposed into eukaryotic targets in vitro? 2. Will Tn7 proteins transpose into eukaryotic targets in vivo? 3. Will Tn7 transposition disrupt normal glutamine-fructose-6-phosphate transaminase (GFPT) expression?